Why does it say "va'Yisogu"?
Radak: They regressed between one judge and another.
Malbim: Hashem's intent was that they go in a path of perfection from level to level. They backtracked to the rebellion of their fathers.
Who were like Avosam?
Radak: The latter were like the earlier Avos.
What is "k'Keshes Remiyah"?
Rashi: It is a devious bow - it does not shoot the arrows where the archer desires.
Radak: A scheming archer shows that he shoots in one direction, but he shoots in a different direction, so those at whom he shoots will not guard themselves. The archer turns in a moment to the other side. So Yisrael served Hashem in the days of the Shofet, and when he died, they switched in a moment to serve idolatry.
Malbim: It shoots the arrow against its owner (the archer). So, in place of Hashem's intent that they be like arrows in a Gibor's hand to teach to them the true Emunah and to eradicate idols, they returned like an arrow against Him.